The present invention relates to afterloaders and devices to couple to afterloaders. In particular, the present invention relates to the sensing of force related to a device coupled to an afterloader.
In the last several years, minimally invasive surgical procedures have become increasingly common. Treatment of vasculature can be done in a minimally invasive manner. For example, a blood vessel narrowed by an obstruction, such as a stenotic lesion, can be treated by an angioplasty procedure to compress the lesion and widen the vessel to increase blood flow there through. Angioplasty involves the advancement of an angioplasty balloon at the distal end of a catheter to the site of the lesion within the vessel. Once positioned, the balloon is inflated to compress the lesion.
Following angioplasty, the risk of a subsequent restenosis is significant. Restenosis, the re-emergence of a stenotic lesion, is prone to occur at the site of the former stenotic lesion treated by the angioplasty. In order to help avoid restenosis, radiotherapy procedures have been developed that are applied to the site of the former stenosis following angioplasty. These procedures include the advancement of a radiation source to the site of the former stenosis. Application of radiation to the site of the former stenosis can significantly reduce the risk of restenosis.
Radiotherapy can include the use of a radiation source wire as well as other radiation sources. Where a source wire is used, it will be made available to the physician in a secure manner and delivered to a patient by way of a radiotherapy catheter that can be equipped with a centering balloon. The centering balloon will be positioned within vasculature at the site of the former stenosis. The source wire will be advanced through a lumen of the radiotherapy catheter to a distal portion of the catheter. The centering balloon helps keep the catheter lumen centered to allow a more even distribution of radiotherapy.
The source wire is advanced by way of an afterloader. That is, the source wire has been loaded within an afterloader prior to treatment. The afterloader is a machine which stores the source wire and subsequently advances it through a radiotherapy catheter to deliver radiotherapy. The afterloader advances and retracts the source wire through the radiotherapy catheter in an automated manner during the radiotherapy procedure.
It is important that the radiotherapy catheter be positioned such that its lumen is un-kinked and unobstructed as the source wire is advanced there through. For example, if a given automated radiotherapy procedure is carried out with an obstructed lumen, the source wire could be damaged, or worse, pierce the radiotherapy catheter as it attempts to force itself past the obstruction. This could result in directly exposing vasculature to the source wire in an unintended manner and possible harm to the patient. Additionally, placement of the radiotherapy catheter within a highly tortuous vessel can lead to similar consequences if the advancing source wire exerts a force on the catheter that either the catheter or the source wire cannot tolerate.
In addition to a radiotherapy catheter, other devices can be connected to the afterloader to receive an advancing source wire. For example, a physics coupler can be secured to the afterloader to establish measurements or perform calibrations related to the source wire prior to application of a radiotherapy procedure. Additionally, oncology applicators can be secured to the afterloader to receive the source wire. Regardless of the device coupled to the afterloader, an unobstructed lumen will be required.
In order to ensure that the lumen of the device coupled to the afterloader is positioned in a smooth and unobstructed manner when receiving the advancing source wire, the afterloader can be equipped with a dummy wire. The dummy wire, having no radioactive source, can be advanced through the lumen and retracted again to ensure a clear lumen path is present to receive the source wire.
However, the dummy wire, like the source wire, is also susceptible to damage and can cause injury to a patient should it exert a force upon the device coupled to the afterloader that the device or the dummy wire cannot tolerate. Therefore, what is needed is a force sensing mechanism to monitor force in relation to the device.
An embodiment of the present invention provides a force sensing mechanism having a beam with a stationary portion. A housing for an afterloader with a coupling portion to accommodate a portion of a device coupled to the afterloader is coupled to the beam and a force sensor is also coupled to the beam to monitor a force of the device.
An embodiment of the invention includes an afterloader system with a processor and a force sensing mechanism to deliver information to the processor regarding a force of a device coupled to an afterloader. The system includes a cartridge to house the force sensing mechanism.
In a method of the invention a force sensing mechanism having a beam with a stationary portion is provided. A portion of a device is coupled to a housing for an afterloader and the housing coupled to the beam. A device force of the device is monitored.